Abstract: The disclosed technology is generally directed to the compression of inverted indexes. In one example of the technology, an inverted index that includes a plurality of posting lists and metadata is provided. The inverted index indicates compression settings that are associated with the plurality of posting lists. At periodic scheduled times, a regeneration is performed on the inverted index. The regeneration includes decompressing the inverted index. The decompressing uses the compression settings indicated by the inverted index. The regeneration further includes determining compression settings to use during a next periodic scheduled time of the plurality of periodic scheduled times, such that at least a first posting list of the plurality of posting lists uses a different compression setting than a second posting list of the plurality of posting lists.

Abstract: The disclosed technology is generally directed to the compression of inverted indexes. In one example of the technology, an inverted index that includes a plurality of posting lists and metadata is provided. The inverted index indicates compression settings that are associated with the plurality of posting lists. At periodic scheduled times, a regeneration is performed on the inverted index. The regeneration includes decompressing the inverted index. The decompressing uses the compression settings indicated by the inverted index. The regeneration further includes determining compression settings to use during a next periodic scheduled time of the plurality of periodic scheduled times, such that at least a first posting list of the plurality of posting lists uses a different compression setting than a second posting list of the plurality of posting lists.

Abstract: Train detection security system and method for detecting a moving train are provided. The train detection security system includes one or more sensor units fixed to a rail of a rail track. The sensor units are arranged for detecting a first signal induced by a moving train and propagated through the rail. The system further includes a control unit including a signal processor arranged for receiving first sensor output signals representing the first signals from each of the one or more sensor units, processing the first sensor output signals and generating a train warning signal representing characteristics of the moving train based on envelope characteristics of the first sensor output signals.

Abstract: Train detection security system and method for detecting a moving train are provided. The train detection security system includes one or more sensor units fixed to a rail of a rail track. The sensor units are arranged for detecting a first signal induced by a moving train and propagated through the rail. The system further includes a control unit including a signal processor arranged for receiving first sensor output signals representing the first signals from each of the one or more sensor units, processing the first sensor output signals and generating a train warning signal representing characteristics of the moving train based on envelope characteristics of the first sensor output signals.